1. Field of the Invention
The present invention relates to a surveillance system for automatically detecting an intruding object by using multi surveillance cameras and an image processing device, and displaying its enlarged image on a screen.
2. Description of Prior Art
In the field of surveillance equipment in recent years, there have emerged systems which not only display on a screen video signals supplied from cameras but also identify the position of any abnormality that has occurred by analyzing the signals with an image processing device, and presenting images of vicinities of the abnormality to the monitoring personnel.
An example of such prior art is described in the Japanese Patent Disclosure No. 69342/1999 (Patent Reference 1). The Patent Reference 1 discloses an intruding object tracking image processing system which, in order to detect an intruding object, uses a camera having a wide angle lens and displays an enlarged image of the intruding object on a screen by orienting toward the intruding object, identified by image processing, a rotating camera controllable for panning, tilting and zooming in and out.
This surveillance system according to Patent Reference 1 will be briefly described below with reference to FIG. 1. FIG. 1 is a block diagram showing the configuration of an intruding object tracking image processing system according to the prior art. This system comprises a wide angle shooting camera 1001 provided with a wide angle lens, a rotating camera 1002 which can be controlled in panning, tilting and zooming, an image processing device 1003 for analyzing image signals and supplying signals for controlling the rotating camera 1002 on the basis of the result of analysis, a monitor 1004 for displaying image signals from the wide angle shooting camera, and another monitor 1005 for displaying image signals from the rotating camera.
The wide angle shooting camera 1001, used for detecting an intruding object, supplies image signals to the image processing device 1003 and the monitor 1004. The rotating camera 1002, used for displaying the intruding object on an enlarged scale, is panned, tilted and/or zoomed in or out in accordance with control signals entered from the image processing device 1003, and supplies image signals to the monitor 1005. The image processing device 1003 comprises intruding object tracking means 1006 for keeping track of an intruding object and camera control means 1007 for generating control signals to be supplied to the rotating camera 1002. The intruding object tracking means 1006, utilizing image signals entered from the wide angle shooting camera 1001, detects, and identifies the position of, the intruding object by combining them with existing elements of image processing including background differences.
When the position of the intruding object has been identified, the camera control means 1007 generates a control signal which enables the rotating camera 1002 to shoot the intruding object in the orientation in which the intruding object is present in an appropriate size, and supplies the picked-up image to the rotating camera 1002. Upon receiving the control signal, the rotating camera 1002, in accordance with the control signal, rotates the camera in the orientation in which the intruding object is present and zooms in on the object for enlarged displaying. The monitor 1005, which displays image signals from the rotating camera 1002, displays an enlarged image of the intruding object.
However, whereas two cameras are used according to the above-cited example of the prior art, detection of an intruding object with a single wide angle shooting camera is inevitably susceptible to a blind spot, near the position in which the wide angle shooting camera is installed, in which the intruding object cannot be detected.
FIG. 2 is a schematic diagram illustrating the disadvantage of the above-cited example of the prior art. As shown here, if for instance a wide angle shooting camera 1102 is installed on a ceiling 1101 and any intruding object is to be shot from the ceiling 1101 in a looking-down position, an area 1103 immediately below the wide angle shooting camera 1102 will not be covered by the field of view 1104 of the wide angle shooting camera 1102 and become a blind spot in which no intruding object can be detected. Therefore, in order to detect an intruding object in the blind spot 1103, another wide angle shooting camera will have to be installed, entailing an expanded scale of hardware.
An object of the present invention, attempted in view of this disadvantage of the prior art, is to provide a surveillance system capable of displaying an enlarged image of an intruding object with no blind spot with the minimum number of cameras by operating multi-camera in coordination, including a rotating camera controllable for panning, tilting and zooming in and out.